Field of the Invention
The present invention relates to an image forming apparatus using an electrophotographic system.
Description of the Related Art
In image forming apparatuses using an electrophotographic system such as copiers, printers, facsimile machines, and multifunction peripherals including copiers, printers, and facsimile machines, it has been known to use a process cartridge system in which photosensitive drums and processing means acting on the photosensitive drums are unitized as integral cartridges and made attachable/detachable to/from apparatus bodies. In the image forming step of an image forming apparatus, light such as laser light, LED light, and lamp light corresponding to image information is irradiated onto a photosensitive drum to form an electrostatic latent image thereon. Then, the electrostatic latent image is developed by a developing apparatus, and a developer image formed on the photosensitive drum is transferred onto a recording material to form an image thereon. In the above step, when attached to an apparatus body, a cartridge (unit) needs to expose its position at which the photosensitive drum opposes the recording material and its portion at which the photosensitive drum opposes body-side processing means acting on the photosensitive drum. In the replacement of the cartridge, the cartridge needs to be inserted so as not to contact the apparatus body to prevent damage on the surface of the photosensitive drum.
In view of the above problems, there has been proposed, as a method for inserting a cartridge, a configuration in which a rib serving as an inserting/extracting guide is provided on a door that opens/closes the opening portion of an image forming apparatus for replacement and the cartridge is mounted on the rib to be attached (Japanese Patent No. 5787490). Besides, there has been proposed a configuration in which a protection cover removable in a longitudinal direction is provided on a cartridge, a convex portion provided at the tip lower portion in the inserting direction of the protection cover is fitted in the concave portion of an image forming apparatus body, and the cartridge is guided in a state of being attached (Japanese Patent No. 3535604).
However, in the configuration in which the cartridge is attached in a state of being mounted on the rib, the height of the cartridge with respect to an apparatus body is made substantially the same between a state in which the cartridge is attached inside the image forming apparatus and a state in which the cartridge is mounted on the rib. Accordingly, in a configuration in which a photosensitive drum is exposed to the upper side of the cartridge, there is a likelihood that the cartridge contacts the apparatus body and damages the surface of the photosensitive drum when the cartridge is isolated from the rib.
Further, in the configuration in which the cartridge is guided by the protection cover to be attached, there is a concern that the function of guiding the cartridge is lost when a user erroneously removes the protection cover before attaching the cartridge to the apparatus body.
It is an object of the present invention to provide a technology capable of preventing the occurrence of damage or the like on members constituting a unit in a configuration in which the unit is made attachable/detachable to/from an image forming apparatus body.